Ammeter



June 3, 1930. J. E. ESHBAUGH AMMETER Filed Oct. 7, -192'7 g narran .sra

, .Inssn E; nsnnnein or FLINT, Micnrenn, Assrenoniro A espinal; :entre concentra* i 0F FLINT, MICHIGAN, A COMPANY 40F .MCIQHGAN "Patent/ed June 3, 1930 AMI/LETER Application' iefroctober 7, i927. Serial 119,224,641.

rl`his invention relates to an ammeter andv ymore particularly to an ammeter of the type ordinarily mounted on the dashboard and magnituderof thef'currentthrough the of' an automobile to indicate' the direction electrical system.

The prime requisite of an ammet'erof this type is simplicity. Economy of production isifvitalfand -itisessential that the device -be composed of a minimum number of parts; ammeter of this type is ordinarily mounted `in a small aluminum case and includes -a conductor, a permanent magnet, an *indicatingl needle which is mounted on ashaft lcarrying an armature of magnetic material, and a dial 4for indicating the positionfo the needle.l :,The' 'conductor is -arranged parallel to the line between the .poles of the v magnet so Vwhen a current passes through the conductor, the position of ythe armature, V'and 'hence the needlek mounted on'the same shaft,;w'ill be tlieresultant of the lforce of the unvarying permanent 4magnet andthe magnetic flux," the lines of which extend circumferentially about the 'conductor,r -thisilux' varying in' magnitude and di- Y rection with the current. f It is Well known that the intensity of ak Y magnetic field atfa-,point'adjacent a conduc- 30 tor varies inversely with the distance `from that point to the conductor.r Hence, when .tion-'of thearmature, it moves ythe armature @some distance from/t-he'conductory and into 'afw'e'aker field'.Vv The 'next unit of current strengthens thisifield but does not make it strong enough to move thearmatu're 'the same distancefthe ir'st'unit did." Inanam;

- `n is' the fobja of the ,present inventan to iso construct andV locate theVpart's-that upon' tationfot the armature; l 011e e Side moves to 1 a field .of less intensity while the ether side moves'ita field 0f greater .in-

.tensityf This arrangement compensates to Y a great vagitent{ft-lie1inaccuraciesv resulting irQIll .the previouslconstructions :and secures a more nearly equal deflection for each additional unit of'cur'rent. f

Other objects of the invention will appear in the course of the following description,v

taken in connection with the accompanying drawing and appended clai-ms.

In the drawing: V l Figure l` is a plan view with parts broken away. f

Figure 2 is an end view with par-t of the casebroken away substantially on Vthe vline 2 2 of Figurelp f Figure 3 is a section on the line 3 3 of Figure l.y f

Figure i is a sectional iview similar 4to Figure 3 showing a slightly modiiied form of my invention. f-

Figure 5 is a section on -the Figa;y f -1 F Figure 6 is a section on the line"6 6 of 4ig. 4- 4 Referring tothe drawing, the numeral l() yindicates a substantially cupshaped` Case which is flared out at its rim; rlhiscase line 5 5 of is ordinarily constructedIv of aluminum.

flows.y lVhile I' have `shown'two loops in the coil, .the exact number islimmaterial as one may be Tsuicient or more than one des-irable.` Terminal bolts 14 passvthroughfthe terminals-of ,this coil and throughcorres` spending apertures in nthev bottom of 'the case, being heldL from contact therewith by insulating washers 16.l A strip y18 oflinsulating 'material is placedfbetween the coil andthe bottom xofthecase.` Fixed to the bottomzoflthe casebyl means Aoa'bolt forrivet 20 is a one-piecefme'tal'lic framek 22 whichfextends upward and 'has a horizontal .portion on which Ythe;v dial .is

supported. f A `central strip from" the? hori- Zontal and fverticaLportions of 'fthe 'frame' 22" `is 4bent Ydown inthe formV ofV a tong-ue as. at 24 and the ...opposed surfaces prick soV Y fleeting the armature''than would beY possible.

punched V,to provide bearings for the coneshaped ends of the shaft 26 on which are mounted the indicatingv needle 30 (having a'balancing tail 31) and the armature 28,

' 5 the plane of the latter being parallel to the plane of the coil. VThe armature is Yof magnetic metal and is .readily held on the Ashaft` by the tensionof the metalj. ByY placingthe armature as it is,.I am enabled to use al greater portion ofthe magnetic field Jfor deif the' armature were ina plane perpen-4 dicular to the shaft 26, This. provides ank armature ythat is responsive to'. smallerl changes. in current the'case. f Supportedin the bend .in-the frame 22fis a horseshoe magnet 32 held in place by bent than would otherwise be down portions 34 of the frame 22. f Riveted 0 to the frame 22 is the dial 36whch is pro-.f Y vided'with an arcuate slot 38or permitting swinging of the oiset indicatingneedle 30.

At'40 Iphave indicated the usual glasscover andat 42the beZelor holding the coveron the case.. .1 .l l The operation yof the. device will now be def scribed. By lreference to Figure .1, itis noted that as the armature rrotates clockwise',

passes through thecoil, the'inagneticieldV t thereabout tends to .turn the armature at position oit the armature willbe the resultant of the. force ofthe permanent magnet vand the orceof the magnetic flux 'aboutitlae the needle andarmature jarehxed .to the shaft 26,the position of the armature will be indicatedbythe yposition of the needle on the dial. VThe needlethus indicatesthe v` direction.; and magnitude .of flowjf'of current throughthe coilgof the conductor;V i

' y"While Il "haveshown thepresent ammete f Y. as mounted in` alcasefit is Vobvious thatit t may be mounted ink any other desired .way as withinv a separate instrument gpanelg or fixed vdirectly to theidashboard".ofacar. .If have described therelation ofth'e parts/as par-A Vallel or perpendicular,etc.,r butit must/bev .understood-that'theseterms are used ina y general Vsens`e,las no great mathematical acf-V curacy 'is possible or .even necessary. In AFigures'4, 5i and G--Ihave illustrated a slightlymodiiedy form Vof my inventiouiin which the one piece supporting 4frame '50..for thedial, horseshoe or U-shaped magnet 32., shaft v 26, armatur`e k28 and' needle 30y is .lines at 13VK and "are connected withthe heads .magnetatthe vcorners on .the inside of .its 'arms'.v Infaddition thebase;y -portion of lthe '34 andthe-back and top portions' yof. the frame 50.5 t A Vingistaken fromY the inner part of'the-rfrdm@ right angles to its illustrated position.'l The y )to VbeV shoved up conductor 'during passage of the current. As! l tions en. .Said .flame t0 rigidly hldisaid- '11.

1 3.1 Thestructure of' claim 2,-a`.ma gnet,and

:pressed out Aportions o'nifsa'id frameV for t V rigidly"holdingsa'id maghetto saidframe Y f i" InV an ammeteigfa- U-"s'haped, "one-invecer f* Vof'said frame rigidly Yhololingfisaidmaterial,

provided with Va Vlaterally'spacedy base :por-.-

tion 52 slotted as at k53 lto extend about the l terminal bolts 56 and spacedtherefrom'and. f f

from the casing'. 10 by strips 58'Vand` 60pt, insulating materi`a1,. .The Vbase portion 52 is provided with ank inturnedend '54 and av.

.tab 62 forholdingthe `up'per-Minsulating strip i' i 58 inposition.l Theterminals of the conductor l2 are-extendedv as shown in dotted v. .'75 of thev respectivetermlnal bolts. This struc- .p ture didersfrom the 'lrstfembodiment disclosedin that it renders unnecessary use of Ythey fasteningk bolt 20.V The structure andV operationfareotherwise'the ysame as that describedV in` the r'st embodiment described.V

Injthe species shown infliigsjv 4, 'and' 6,v the magnet 32-.is held in place bynieans of ingers34-, thependsV of whichy areybent away from eachV other asshown at vrand gripthe magnet 32 yis wedged between thehngers With the described construction shown'in.V Figs. 4, 5 and 6, itis possible to' have a subassembly consisting ofconductor 12,-studsfV 56 and insulator 58 Vwhich vsub-assemblyis rigidly* held togetherby turning over suitand may be later dropped'wnto place inthe Y t CaiselO.v n* "y Itis also to be notedthatthelowerpartof v, i 'Y Y Y tongue 24 which -formsthelower Vpivot bear! instead of .from an extension,l thereofas y customaryhn priori.constructions.v This Y f structure Vhas two. advantages; ,.f'1r`st, it saves metal;` second, lit permits 'the conductor/l2 closer to thearmature with-y out interference. v

A I-claim:

supporti-ng trame, a v"tongue thereonlga POHtel 'Pivotally mountedajbetween' said* I tongue vand trame, ,insulation ,material on.y i

said frame to insulate said Yframe ,andme'chaniSIIlIOm the casing, andpressedfoutpo .2. lanf rarnnneter",Y lsiippoisting iframe i having aislottedportion,:insulating:material Y :,lf i i i above {and}below;sad portion, terminalsY f 12o j Y.

passing through jsaid f' insulating? pmaterifal'y and lente'rlngsaid slots,and pressedfout .porj tions ofA said trame re'z'aining'y a part loffsaid insulating .materiali Y frame, linsnlatonj material' V.mounte2T-on one 4' legv ofk the U, 'integraltonguelor tab portions p able ingers or tabs such as y24, 35,54 and'62, l

1.111 an .ammeter,a casing, a one-piece gno i i ".l

an integral tongue formed on'said frame and having a portion extending parallel t the legs of the U, a pointer swinging mechanism mounted betweensaid tongue and one ofthe legs,fand a magnet mounted on said frame.y

5. The structure of claim 4, said magnet being U-shaped, and integral tongue portions'of said frame retainingsaid magnet at y its inner side.

6. The structure of claim 4, said magnet mounted` inside the U at one leg and abutting the base of the U. l

7. VThe structure of claim 4, said tongue pressed from a leg and the base of the U.

8. The structure of claim 4, said tongue or tab portions comprising a tongue or tab -at the endof a leg of the U, and atongue f V,or'tab pressed from the base ofthe U.

f "said leg and the casing.

z secured to one leg of said U-shaped frame.

9. The structure of claim 4, said ammeter lhaving a casing, and said frame secured to said casing at one ofV said legs by means of terminals passing .through the insulation,

l0. The structure of claim 4, and a dial 11. In an ammeter, a U-shaped one-piece Y frame, insulation material mounted on one ,leg of the VU, integral tongue or tab portions of said ,frame rigidly vholding said material,

an integral tongue formed on said frame and having a portion extending parallel to the -legs of the U, a pointer swinging mechanism Y mounted between said tongue and one of the legs, one of the legs of the` Us having an opening Vtopermit passage of the pointer, and a magnet mounted on said frame. v

l2. In an electrical measuring instrument, a U-shaped frame, a tongue pressed from a i @leg and the base of the U so as to leave a slot,a pointer swingably mounted between said tongue and oneof the legs'of the U, a

o In testim biasing magnet,'and tongues pressed from the frame at said slot to hold said magnet.

' 13. In'an ammeter, a U-shapedV supporting frame, kan integral tongue `pressed inwardly of the `U from one leg thereof and underlappingsaid leg, and a pointer-swing- ,f ing mechanism mounted between said tongue and said leg.v Y Y Y y ony whereof I aHiX my signature.

JESSE E. ESHBAUGH. 

